Backup to tape successful – when restoring can’t see for 3 mailboxes individual items for GRT restore. According to user the only difference is that those 3 mailboxes are more than 2 GB in size.
I would suggest logging a support case and having this troubleshot by a live technician. Outside of that you could try duplicating the backup set to disk and verifying as to whether or not your GRT selections are visible for those three boxes
